The invention concerns equipment for unraveling threads from a fabric, in particular cross-threads in the end areas of the fabrics of papermaking machines.
Frequently a so-called spiral seam is used to join the ends of the fabrics of paper-making machines (H. Kerber, nahtprobleme an Trockensieben und -Filzen, Wochenblatt fuer papierfabrikation, p 817-820 [1969], Nr. 19). To make such seams, a set of cross-threads each spaced from the two end edges of the fabric is removed so that only lengthwise threads remain in this area. A plastic spiral is then placed in each place into these longitudinal threads and across the entire width of the fabric of the papermaking machine. Thereupon the particular fabric part is folded over between the spiral and the end edge and sewed together with the remaining part of the fabric. Thereupon the spirals form the edges of the two fabric ends. The spiral seam is closed by the two spirals being inserted into each other so far that a so-called slip-in wire can be inserted into the eyelets so formed.
While in many a way the spiral seam has been found advantageous, its implementation however does remain time-consuming, with the removal of the cross-threads--called unraveling--being especially costly in time. This is still done by hand using an unraveling needle. By means of such an unraveling needle, cross-threads are pulled, parts at a time, out of the fabric and then are cut by hand. As a rule, several of these cross-threads must be unraveled, and furthermore the fabrics of papermaking machines frequently are more than 10 m wide, so that the unraveling takes a very long time. Furthermore, this is a much monotonous and hence psychologically undesirable work which is rendered more difficult in that the position of the body is disadvantageous but can be hardly changed. Lastly, the eyes tire very rapidly because the thin threads are hard to spot. These fatigue phenomena entail other health problems such as headaches and the like.